Trends in weight-related morbidity and mortality are the focus of 2
articles in this issue of JAMA. First, Flegal and
colleaguesArticle used nationally representative data from
NHANES I, II, and III and follow-up data collected through 2000 to estimate
the number of excess deaths in 2000 associated with body mass index (BMI),
categorized as underweight, normal weight, and obese. They found that compared
with normal weight, both underweight and obesity were associated with increased
mortality, and the risk associated with obesity declined over time. In the
second article describing 40-year trends in cardiovascular disease risk factors
by BMI categories, Gregg and colleaguesArticle report that
the prevalence of high cholesterol levels, hypertension, and current smoking
have declined, particularly among overweight and obese persons. Diabetes was
the only risk factor found to have a stable prevalence over the 40 years.
In an editorial,Article Mark discusses challenges in assessing
obesity-related health risks.

Blood Mercury and Neurobehavioral Function

Although fish consumption is encouraged for older adults, fish are known
to contain the neurotoxicant methylmercury, which might contribute to cognitive
decline. To assess this possibility, Weil and colleagues investigated the
association of blood mercury levels with neurobehavioral test scores in adults
50 to 70 years of age. After adjusting for many factors associated with cognitive
decline, they found no definitive evidence that blood mercury levels are adversely
associated with neurobehavioral test scores in older adults.

Live donor renal transplantation may narrow the existing gap between
organ need and supply for patients with end-stage renal disease, but many
patients and their willing donor are not compatible. Kidney paired donation
(KPD), where an incompatible donor/recipient pair matches a kidney with another
incompatible donor/recipient pair, may offer an opportunity to optimize the
use of live donor kidneys. To assess the impact of an optimal KPD program,
Segev and colleagues conducted a simulation exercise comparing transplant
numbers and outcomes under a national matching algorithm with existing local
and regional match options. They found that a national matching program would
result in more transplants with less HLA disparity between donors and recipients
and a reduction in the number of donor/recipient pairs required to travel.

Low-birth-weight infants have an increased risk of cardiovascular disease
(CVD) in adulthood, for reasons that are not fully understood. To explore
potential mechanisms, Kwiterovich and colleagues analyzed cord blood samples
for levels of cholesterol, triglycerides, low-density and high-density lipoprotein
cholesterol, apolipoproteins, lipoprotein subclasses, and lipoprotein density.
The authors identified a subclass of large high-density lipoprotein enriched
in apolipoprotein C-I—a known promoter of hypertriglyceridemia, atherosclerosis,
and apoptosis of cultured human arterial smooth muscle cells—which was
elevated in infants of low birth weight compared with infants born small for
gestational age.